It's a process that's gone on for so long few people have noticed it: the waning influence of the once-mighty federal Treasury.
There was a time, 40 years ago, when Treasury sought to monopolise the economic advice going to the federal government. But those days are long gone.
The peak of Treasury's influence came with the sweeping micro-economic reforms and opening up of the economy in the 1980s and 1990s. It first convinced its minister, John Howard, of the need for widespread reform, but he made little progress under Malcolm Fraser.
Under a much more sympathetic Bob Hawke, Howard's successor as treasurer, Paul Keating, delivered on Treasury's reform agenda beyond its wildest dreams.
Since 2000, after Howard as prime minister won Treasury's 25-year battle to introduce a broad-based consumption tax, it's been largely downhill all the way on micro reform, with its loss of momentum, direction and purity of motive.
This is what's so significant about the Productivity Commission recently seizing the initiative to Shift the Dial and revive and redirect the reform agenda. Its "new policy model" could never have come from a tired and hidebound Treasury.
When Fraser sought to punish Treasury in 1976 by dividing it in two, Treasury and Finance, the initial judgment was that he'd succeeded only in doubling its vote in favour of budget rectitude at the cabinet table.
Forty years on, I now doubt that. Its bifurcation has diminished Treasury's effectiveness in the endlessly recurring task of "fiscal consolidation" (getting the budget deficit down) by robbing it of both the expertise and the motivation to find innovative, politically sustainable ways to limit the growth in government spending.
This trickier side of the budget has largely been left in the hands of the Finance accountants, whose vision rarely extends beyond this year's budget task, and who know more about creative accounting than the wider economic consequences of their crude spending cuts.
On the revenue side, Treasury shares the Business Council's unending obsession with tax reform. Why? To a surprising extent, for the simple, institutional reason that tax policy still lies within its own ministerial responsibility.
Treasury's become more inward looking and less concerned to oversee ("co-ordinate") the activities of other departments.
With one glaring exception. Treasury's greatest loss of influence came with the recognition of Reserve Bank independence in the mid-1990s.
From that time, the day-to-day management of the macro economy moved to the Reserve, with Treasury merely retaining a seat on the bank board and the ear of the treasurer.
Yet there's been great reluctance on Treasury's part to acknowledge this loss of power. It pretends nothing's changed, devoting far too many of its shrinking human resources to second-guessing the Reserve.
The Reserve devotes many resources to "liaison" (gathering businesses' views on the state of the economy), so Treasury must do it too.
The Reserve has an extensive forecasting round each quarter, so Treasury must do its own – but half-yearly, because its only actual forecasting need is for a set of macro-economic "parameters" to plug into its budget estimates of spending and revenue.
The Reserve regularly investigates the latest macro puzzle – say, why non-mining business investment is so slow to recover – so Treasury must do its own. Its new Treasury Research Institute focuses on macro management issues.
What gets neglected is Treasury's oversight of the big micro reform issues. Think health, education, infrastructure. Without an institutional understanding of the detail of these areas, Treasury simply isn't up to speed on either micro reform or budget sustainability.
So its recent establishment of a "structural reform" division seems a step in the right direction – until you learn that the group's first big project was to inquire into non-mining business investment's slowness to recover.
Another part of Treasury's decline is its politicisation, particularly Tony Abbott's decision to sack the Treasury secretary, Dr Martin Parkinson, and replace him with someone whose views he felt more comfortable with, John Fraser.
Recent Coalition governments have preferred Treasury and other departments to be less the fearless policy advisers and more the handmaidens to the minister and their office.
This politicisation makes it ever-harder to believe Treasury's persistently over-optimistic economic and budget forecasts are the product of forecaster fallibility rather than political interference.
Trouble is, the more your influence and authority decline, the more people want to take a crack at you.
Should Labor win the next election, it says it will shift responsibility for budget forecasting and the five-yearly intergenerational report (whose credibility Joe Hockey destroyed by turning it into a political tract) from Treasury to the more independent Parliamentary Budget Office.
